Communication service providers often implement Virtual Private Networks (VPNs) for their customers. For example, VPNs may be provided using Internet Protocol (IP), Border Gateway Protocol (BGP) and Multiple Protocol Label Switching (MPLS) in accordance with the techniques disclosed in Internet Engineering Task Force (IETF) Request for Comments (RFC) 4364, entitled “BGP/MPLS IP Virtual Private Networks (VPNs),” which is incorporated by reference herein. The companion standard for VPNs in IPv6 networks is RFC 4659, entitled “BGP-MPLS IP Virtual Private Network (VPN) Extension for IPv6 VPN,” which is also incorporated by reference herein. IP VPN services based on RFC 4364 and RFC 4659 have been deployed extensively by service providers around the world.
VPNs configured in accordance with RFC 4364 and RFC 4659 connect customer sites via tunnels, and allow IP unicast packets to travel from one customer site to another. However, these VPNs do not provide a way for IP multicast traffic to travel from one customer site to another.
The unicast VPN services defined in RFC 4364 and RFC 4659 can be extended to include the capability of handling IP multicast traffic, using the techniques disclosed in RFC 6513, entitled “Multicast in MPLS/BGP IP VPNs,” which is incorporated by reference herein. VPNs configured in accordance with RFC 6513 are considered examples of what are more generally referred to herein as multicast VPNs (MVPNs). Such MVPNs are typically configured to support the transmission of IP multicast packets between customer sites using multicast tunnels.
MVPNs in which all sender and receiver sites are associated with the same customer may be viewed as examples of what are commonly referred as “intranets.” Some MVPNs encompass sites that are associated with different customers, and such MVPNs may be viewed as examples of what are commonly referred to as “extranets.”
Accordingly, it is known to configure a given MVPN with extranet functionality so as to allow multicast sources associated with one customer to send multicast traffic to multicast receivers associated with other customers and similarly to allow multicast receivers associated with one customer to receive multicast traffic from multicast sources associated with other customers. Multicast sources in an MVPN extranet are referred to as “extranet sources.” The multicast groups to which the extranet sources generate traffic are referred to as “extranet groups.” The receivers that receive multicast traffic from extranet sources are referred to as “extranet receivers.”